Orangutan

• 1. Introduction

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  Orangutans are the only great apes native to Asia, and for millions of years they ranged across Southeast Asia and South China. Today they survive in a fraction of that territory, confined to parts of Borneo and Sumatra. What does it mean that these red-haired, long-armed animals are now critically endangered on every island they call home? And what does science keep discovering about minds that can plan routes through the forest, apply medicine to wounds, and whistle for the sheer pleasure of it? The story of the orangutan is one of ancient lineages, startling intelligence, and a present-day crisis that researchers like Biruté Galdikas have spent their lives trying to reverse.

• 2. A Name With Deep Roots

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  Jacobus Bontius, a Dutch physician, recorded the word for the ape in 1631 in his Historiae naturalis et medicae Indiae orientalis. He noted that Malays claimed the animal could speak but chose not to, lest it be put to work. That detail tells us something important: Western writers from the start had trouble separating the orangutan from the human.

  The name itself comes from the Malay words orang, meaning person, and hutan, meaning forest. The phrase referred originally to forest-dwelling people; when Europeans adopted it for the ape, they imported a category confusion that would haunt the animal's image for centuries. The first recorded Malay use of the term applied to the ape identifies it as a Western coinage, though there is evidence the phrase circulated in premodern Old Malay as well.

  The word reached English in 1693, when physician John Bulwer wrote it as Orang-Outang. Linguists believe the English form entered through Portuguese, which would explain why the letter h from hutan dropped out. Modern Malay and Indonesian actually borrowed the word back from English or Dutch in the 20th century, acquiring it without the original h. Meanwhile, the genus name Pongo traces to a 16th-century account by Andrew Battel, an English sailor held prisoner in Angola. He described two creatures named Pongo and Engeco; he was almost certainly describing gorillas, but the label stuck to the Asian apes when French naturalist Bernard Germain de Lacépède applied it to the genus in 1799.

• 3. Three Species, One Lineage

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  Carl Linnaeus placed the orangutan in the genus Homo when he first described it scientifically in 1758, filing it under the name Homo troglodytes. That classification would not survive long. By 1760 it had been renamed, and by 1799 it carried the genus name Pongo. For most of Western science's engagement with the animal, all orangutans were treated as one species.

  That changed in 1996, when molecular evidence confirmed that the Bornean orangutan, Pongo pygmaeus, and the Sumatran orangutan, Pongo abelii, are distinct species. Then in 2017 came a genuine surprise. Researchers announced a third species, Pongo tapanuliensis, living in the Batang Toru forest of Sumatra south of Lake Toba. The surprise was its genealogy: despite sharing an island with the Sumatran species, the Tapanuli orangutan is actually more closely related to its Bornean cousins. A 2017 genome study found that the Bornean and Tapanuli lineages diverged from the Sumatran line about 3.4 million years ago, and from each other around 2.4 million years ago.

  The Sumatran orangutan's genome was sequenced in January 2011, making it the third great ape after humans and chimpanzees to have its genetic blueprint fully mapped. Researchers noted that Bornean orangutans show less genetic diversity than their Sumatran relatives, despite the Bornean population being six to seven times larger. Fewer than 800 Tapanuli orangutans are estimated to remain today, placing them among the most endangered great apes on earth.

• 4. Body Built for the Canopy

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  Adult male orangutans stand roughly 137 cm tall and weigh around 75 kg; females are considerably smaller, typically 115 cm tall and about 37 kg. The tallest orangutan on record measured 180 cm. A male's arm span reaches about 2 m, proportionally far longer than a human's, and those arms serve a constant purpose: orangutans are the most arboreal of all the great apes, spending the bulk of their lives in trees.

  The hand is a precise instrument. Four long fingers curve naturally into a suspensory hook grip, while the thumb sits dramatically shorter than a human's, keeping it out of the way when the fingers wrap around a branch. The feet are equally dexterous, with four long toes and an opposable big toe that functions much like a hand. Hip joints allow the legs to rotate in a range similar to the arms and shoulders, giving the animals remarkable reach in every direction through the canopy.

  Orangutans do not knuckle-walk the way gorillas and chimpanzees do. On the rare occasions when they descend to the ground, they bend their digits and walk on the sides of their hands and feet. Coloring starts bright orange at birth and darkens toward maroon or chocolate as the animal ages. Dominant adult males develop large cheek pads, called flanges, made mostly of fatty tissue supported by facial musculature, along with pronounced throat pouches that act as resonance chambers for the long, booming calls they use to attract females and warn off rivals.

• 5. What They Eat and How They Live

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  Fruit drives the orangutan's day. Foraging for it can consume 57-80% of their time, and even during seasons of scarcity, fruit still accounts for around 16% of feeding time. Figs are a particular staple, along with drupes and berries. Orangutans are thought to be the sole seed disperser for some plant species, including the vine Strychnos ignatii, which carries the toxic alkaloid strychnine.

  Leaves fill the gaps, making up roughly 25% of average foraging time. During lean periods, the apes appear to depend heavily on the leaf and stem material of Borassodendron borneensis. The diet also extends to bark, honey, bird eggs, insects, and occasional small vertebrates including slow lorises. Some populations practise geophagy, consuming soil from cliff sides and earth depressions, possibly because the kaolin minerals in the soil counteract toxic tannins and phenolic acids in their food.

  Orangutans also treat their own injuries. During a 2022 field observation, a male Sumatran orangutan known to researchers as Rakus chewed leaves of the Fibraurea tinctoria vine and applied the mashed material to an open wound on his face. Primatologists who had been watching Rakus at a nature preserve reported that within five days the wound was closed and within a few weeks it had healed to a small scar. The plant has known anti-inflammatory properties.

  Socially, orangutans are the most solitary of the great apes. The most reliable bonds form between mothers and their dependent offspring; resident females maintain defined home ranges that may overlap with those of female relatives. Flanged males hold larger ranges that encompass one or several female territories, and they are typically hostile to other males of either type.

• 6. Intelligence and Culture

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  Zoo Atlanta installed a touch-screen computer for its two Sumatran orangutans to play games on, and the animals took to it. That image captures something real about orangutan cognition: these are primates that engage actively with novel problems and seem to enjoy doing so.

  A 1997 study at the Leipzig Zoo placed two captive orangutans in a cooperative pulling task without any prior training. They succeeded in retrieving food on the very first session, and over the course of 30 sessions they became faster and better coordinated. A 2008 study at the same zoo found evidence for what researchers called "calculated reciprocity": one animal helping another in apparent expectation of being repaid. Orangutans were the first non-human species documented behaving this way.

  In the wild, flanged males plan their travel routes in advance and signal them to nearby individuals. Mother orangutans remain silent when a threat is present and wait until the danger passes before producing an alarm call, a delay that teaches offspring about what the predator was. Bonnie, an orangutan at the US National Zoo, was heard spontaneously whistling after listening to a caretaker whistle, apparently without expecting a food reward. Researchers interpret this as controlled manipulation of the vocal folds, a capacity they link to the origins of human speech.

  Tool use has been particularly well documented. Primatologist Biruté Galdikas first observed it in ex-captive populations. In Suaq Balimbing, orangutans developed a toolkit for foraging that included insect-extraction sticks for hollow trees and seed-extraction sticks for hard-husked fruit. Wild orangutans in Tuanan, Borneo, were found to hold leaves against their mouths to amplify kiss squeak sounds, apparently making themselves seem larger. A 2003 comparison across six field sites found that each orangutan population used different tools, and the extent of the differences grew with geographic distance, suggesting cultural transmission rather than independent invention.

• 7. Biruté Galdikas and Human Contact

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  When Biruté Galdikas arrived in Borneo in 1971, almost nothing was systematically known about how orangutans behaved in the wild. She settled into a primitive bark-and-thatch hut at a site she named Camp Leakey, in Tanjung Puting, and she would spend the next four years developing her PhD thesis for UCLA there. Along with Jane Goodall and Dian Fossey, she is counted among what became known as Leakey's Angels, named for anthropologist Louis Leakey.

  Galdikas reported that orangutans were already threatened by poaching and deforestation when she started her work. By the 2000s the picture had grown considerably worse, with habitats shrinking from logging, mining, road-building, and the conversion of forest to palm oil plantations driven by international demand.

  Europeans had been aware of orangutans since the 17th century, and the apes' relationship with human society has been layered and often disturbing. Explorers in the 19th century hunted them heavily in Borneo. In 1817, an orangutan joined the collection at London's Exeter Exchange; he rejected the company of other animals except a dog, preferred humans, and was occasionally taken on coach rides dressed in a smock-frock and hat. The London Zoo housed a female named Jenny who wore human clothing, learned to drink tea, and was visited by Charles Darwin, who compared her responses to those of a human child.

  In 2003, a female orangutan was rescued from a village brothel in Kareng Pangi, Central Kalimantan. She had been shaved and chained. Since her rescue, she has been living with the Borneo Orangutan Survival Foundation under the name Pony and has been re-socialised to live with other orangutans.

• 8. Crisis and Conservation

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  All three orangutan species carry the same designation from the IUCN: critically endangered. A 2018 study found that Bornean orangutans declined by 148,500 individuals between 1999 and 2015 alone. A 2016 estimate put the Sumatran population at around 14,613 animals, roughly twice earlier estimates, while the same year's count for Borneo suggested about 104,700. Fewer than 800 Tapanuli orangutans are believed to survive.

  Poaching takes animals for bushmeat, and bones are reportedly sold in souvenir shops in Indonesian Borneo cities. The illegal pet trade is also persistent: mother orangutans are killed so their infants can be sold. Between 2012 and 2017, Indonesian authorities working with the Orangutan Information Center seized 114 animals, 39 of which were pets.

  The largest rehabilitation operation is the Borneo Orangutan Survival Foundation, founded by conservationist Willie Smits. One of its programs is the Nyaru Menteng Rehabilitation Program, established by conservationist Lone Drøscher Nielsen. In May 2017, the BOS rescued an albino orangutan from a remote village in Kapuas Hulu; volunteers noted that albino orangutans are estimated to occur roughly once in ten thousand individuals, and this was the first the organisation had encountered in 25 years of work.

  In June 2008, Spain became the first country to formally recognise rights for non-human great apes, acting on guidelines from the Great Ape Project. In December 2014, an Argentine court ruled that an orangutan named Sandra, held at the Buenos Aires Zoo, must be relocated to a sanctuary in Brazil to provide her partial or controlled freedom. The Orangutan Land Trust, meanwhile, works with the palm oil industry directly, pushing for sustainability commitments and the creation of conservation areas within plantation-adjacent land.